(a) Field of the Invention
The present invention relates to a system and method for operating an optical transponder. More specifically, the present invention relates to a system and method for maintaining and operating signals in an optical transponder having a digital wrapper.
(b) Description of the Related Art
FIG. 1 is a block diagram of an optical transport system to which an optical transponder is applied. As shown in FIG. 1, the optical transport system generally includes a first optical channel unit 120 for receiving a signal transmitted from an optical transmitter 110 to transmit it, an optical multiplexing unit 130 for accepting signals sent from the first optical channel unit to multiplex them, an optical transmission unit 140 for transmitting the optical signal multiplexed by the optical multiplexing unit, an optical demultiplexing unit 150 for receiving the optical signal sent from the optical transmission unit to demultiplex it, and a second optical channel unit 160 for delivering the signals demultiplexed by the demultiplexing unit to an optical receiver 170 of an external system.
In the optical transport system having the above-described configuration, the optical transponder is used for the first and second optical channel units 120 and 160. The optical transponder delivers a client signal transmitted from an external transport network to an optical transport network, transmits a signal sent from the optical transport network to the external transport network, or restores a signal transmitted from the optical transport network and delivers it to the optical transport network again.
A signal generated by a digital wrapper conformable to ITU-T (International Telecommunication Union-T) Recommendation G.709 is obtained by mapping a client signal to a payload, and it has an overhead including information about maintenance of optical signals, performance information, monitoring information, and an error correction code. In general, the digital wrapper has been used for improving optical signal transmission performance using the error correction code. In addition, optical channels can be efficiently monitored and administered irrespective of a transmitter client signal by using the overhead of the digital wrapper. ITU-T Rec G.709 defines the frame structure of the digital wrapper and interface between networks. Therefore, a method of operating the overhead of the digital wrapper is required in order to effectively monitor and administer the optical channels.